In this study we will define a baseline brain biochemical profile for patients with subacute and/or chronic hepatic encephalopathy (HE) using magnetic resonance spectrometry. There are no published criteria, either clinical or biochemical, for the diagnosis of chronic HE in children. There is a need to correlate brain biochemical assay with objective measurements of cerebral function, which we will obtain using neuropsychologic testing. In this pilot study, we will obtain baseline data which will form the basis for dynamic studies of brain glucose metabolism and dietary therapy.